All common storage devices, e.g. hard disk drives, optical disks, flash memories, and magnetic tapes, are implemented as block storage, the appellation “block” signifying that data is read or written on the storage devices as fixed-length bit strings. As a high-level concept, however, cloud storage emphasizes load balancing, extremely high availability, and the ability to scale in and out, and is oblivious to the operation of lower-level storage devices. With the advent of the era of big data, a mechanism is needed to wrap or virtualize block storage devices to an abstract layer so as to render them cloud-worthy.